Will the internal 2kb RAM be disabled if you attach external 16K Ram - as with the ZX81?
/Thomas
Lambda 8300 - screen goes black after a while
Re: Lambda 8300 - screen goes black after a while
https://api.zxinfo.dk/v3/ - ZXDB API for developers
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend
Re: Lambda 8300 - screen goes black after a while
Yes, the internal RAM will be disabled.
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1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Lambda 8300 - screen goes black after a while
I don’t think I’ve asked this, but apart from a multimeter, what test gear do you have?
Also, excluding the keyboard connections, did you do any soldering or desoldering work on this board?
Mark
Also, excluding the keyboard connections, did you do any soldering or desoldering work on this board?
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: Lambda 8300 - screen goes black after a while
Only have a multimeter- but strongly considering an osciliscope.
I have replaced the 7805 and added a ZX8-CCB composite module.
/Thomas
https://api.zxinfo.dk/v3/ - ZXDB API for developers
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend
-
Flatulentia
- Posts: 93
- Joined: Sun May 14, 2023 3:58 pm
- Location: Cambridgeshire, UK
Re: Lambda 8300 - screen goes black after a while
A long shot I know...
If you used the modulator can as the ground connection for the composite video mod, try giving the can a wiggle.
I only mention this as 2 of the 3 ZX81s I've played with had dry joints on both of the modulator can legs that solder through the PCB. This could lead to an intermittent ground to your video mod.
If you used the modulator can as the ground connection for the composite video mod, try giving the can a wiggle.
I only mention this as 2 of the 3 ZX81s I've played with had dry joints on both of the modulator can legs that solder through the PCB. This could lead to an intermittent ground to your video mod.
ZX81 with ZiLOG Z84 CMOS Z80, 32KB battery-backed Toshiba 55257 SRAM with charge status LED, Wilf's "Why Wait?" mod and switch-mode 5V regulator. 50/60Hz mode switch, composite video output with Zigg's back porch mod and 1080p60 HDMI output.
Re: Lambda 8300 - screen goes black after a while
Update: kind of solved... and it points to the worst case scenario, a dying ULA
I managed to source a working Lambda with a working ULA - loaded a few games without any problems. Switched the ULAs and now the "working" got unstable, and the machine in discussion got stable...
With working ULA, both machine now works perfectly - tested with 16K, 32K RAM pack as well as 16K ZX81 RAM pack. So, my conclusion for now is that one of the ULAs are dying (i still can work for a few minutes before going out).
I also noticed that with the dying ULA, only half of the keyboard works
/T
I managed to source a working Lambda with a working ULA - loaded a few games without any problems. Switched the ULAs and now the "working" got unstable, and the machine in discussion got stable...
With working ULA, both machine now works perfectly - tested with 16K, 32K RAM pack as well as 16K ZX81 RAM pack. So, my conclusion for now is that one of the ULAs are dying (i still can work for a few minutes before going out).
I also noticed that with the dying ULA, only half of the keyboard works
/T
https://api.zxinfo.dk/v3/ - ZXDB API for developers
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend
zxinfo-file-browser - Cross platform app to manage your files
https://zxinfo.dk - another ZXDB frontend
Re: Lambda 8300 - screen goes black after a while
There is still no Lambda 8300 ULA replica.
However Tynemouth Software tried to play around with a Minstrel 3 board, and got it to work as a Lambda 8300.
Their findings could be used to create a Lambda 8300 ULA replica.
However I think my hobby electronic knowledge is not suitable for the task.
http://blog.tynemouthsoftware.co.uk/201 ... clone.html
However Tynemouth Software tried to play around with a Minstrel 3 board, and got it to work as a Lambda 8300.
Their findings could be used to create a Lambda 8300 ULA replica.
However I think my hobby electronic knowledge is not suitable for the task.
http://blog.tynemouthsoftware.co.uk/201 ... clone.html
Re: Lambda 8300 - screen goes black after a while
Interesting read indeed
In theory, there is no difference between theory and practice. But, in practice, there is.